netdev - Re: net: dsa: mv88e6xxx: no multicasts rx'd after enabling hw time stamping

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Date:   Wed, 11 Aug 2021 10:49:15 -0500
From:   George McCollister <george.mccollister@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Richard Cochran <richardcochran@...il.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: net: dsa: mv88e6xxx: no multicasts rx'd after enabling hw time stamping

On Thu, Jul 29, 2021 at 8:42 AM Andrew Lunn <andrew@...n.ch> wrote:
>
> > Thanks for the feedback. The datasheet covers the 88E6390X, 88E6390,
> > 88E6290, 88E6190X, 88E6190 so I expect those work similarly but if
> > only the 6352 has been tested that could explain it. It certainly
> > helps to know that I'm working with something that may have never
> > worked rather than I'm just doing something dumb.
>
> I don't think you are doing something dumb.
>
> What i find interesting is that multicast works, until it does not
> work. I would try to find out what call into the driver causes that
> change.
>
> Also, general multicast traffic should not really be involved
> here. The switch should be identifying PTP packets as management, and
> sending them to the CPU port, independent of whatever multicast rules
> are set, flooding of unknown multicast etc. This is needed so that PTP
> frames get through a bridge which is in STP blocking mode. Do you see
> any other problems with management traffic? Do bridge PDUs also not
> work?

Sorry for the huge delay, I had to deal with some other things before
I could get back to this.
When the hardware timestamping is on I don't see packets of type
0x88f7 regardless of multicast destination address. If I change the
packet to 0x88f8 I see it. So, it looks like you are right. Before I
had just tried changing the multicast destination address. I'm still
following up on the other suggestions you've made and hopefully that
will lead to something.

Thanks,
George

>
>         Andrew